Run with colored output even within "pub run".

test/io.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library unittest.test.io;
 
 import 'dart:io';
 import 'dart:mirrors';
 
 import 'package:path/path.dart' as p;
 import 'package:stack_trace/stack_trace.dart';
 
 /// The root directory of the `unittest` package.
 final String packageDir = _computePackageDir();
 String _computePackageDir() =>
     p.dirname(p.dirname(_libraryPath(#unittest.test.io)));
 
 /// Runs the unittest executable with the package root set properly.
-ProcessResult runUnittest(List<String> args, {String workingDirectory}) {
+ProcessResult runUnittest(List<String> args, {String workingDirectory,
+    Map<String, String> environment}) {
   var allArgs = [
     p.join(packageDir, 'bin/unittest.dart'),
     "--package-root=${p.join(packageDir, 'packages')}"
   ]..addAll(args);
 
+  if (environment == null) environment = {};
+  environment.putIfAbsent("_UNITTEST_USE_COLOR", () => "false");
+
   // TODO(nweiz): Use ScheduledProcess once it's compatible.
-  return runDart(allArgs, workingDirectory: workingDirectory);
+  return runDart(allArgs, workingDirectory: workingDirectory,
+      environment: environment);
 }
 
 /// Runs Dart.
-ProcessResult runDart(List<String> args, {String workingDirectory}) {
+ProcessResult runDart(List<String> args, {String workingDirectory,
+    Map<String, String> environment}) {
   var allArgs = Platform.executableArguments.toList()..addAll(args);
 
   // TODO(nweiz): Use ScheduledProcess once it's compatible.
   return Process.runSync(Platform.executable, allArgs,
-      workingDirectory: workingDirectory);
+      workingDirectory: workingDirectory, environment: environment);
 }
 
 /// Returns the path to the library named [libraryName].
 ///
 /// The library name must be globally unique, or the wrong library path may be
 /// returned.
 String _libraryPath(Symbol libraryName) {
   var lib = currentMirrorSystem().findLibrary(libraryName);
   return p.fromUri(lib.uri);
 }